This invention pertains generally to hand-held power tools such as spiral cutting tools.
A spiral cutting tool is a hand-held power tool having an electric motor that rotates a spiral cutting tool bit at high speeds. A spiral cutting tool bit includes a sharp cutting edge that is wrapped in a spiral around the axis of the bit. The spiral cutting tool bit is designed for cutting perpendicular to the axis of the bit. The electric motor that drives the bit is enclosed in a motor housing. The motor housing is generally cylindrical in shape, with the spiral cutting tool bit extending from one end of the motor housing along the axis of the housing. A spiral cutting tool is used to remove material from a workpiece by moving the rotating spiral cutting tool bit through the workpiece in a direction perpendicular to the axis of rotation of the bit. A spiral cutting tool is conventionally operated by grasping the motor housing with one or both hands, turning on the electric motor to begin high-speed rotation of the spiral cutting tool bit, plunging the spinning spiral cutting tool bit into a workpiece, such as a piece of wood, and then moving the cutting tool bit through the workpiece in a direction perpendicular to the axis of the spiral cutting tool bit by moving the motor housing in a direction parallel to the plain of the workpiece surface while keeping the axis of the motor housing generally perpendicular to the workpiece surface.
Precise control of a cut being made by a spiral cutting tool, or any other hand-held power tool, is dependent upon at least two factors: the tool operator maintaining a firm grasp on the tool, and good visibility of the workpiece at the point of the cut.
Various methods have been employed to ensure that an operator may maintain a firm grip on a hand-held power tool. With extended and continuous operation, the motor housing of a spiral cutting tool can become warm, and cutting tool vibrations may cause an operator""s hands and arms to become fatigued. Extended and continuous use of a spiral cutting tool by grasping the motor housing can, therefore, become uncomfortable, reducing the ability of the operator to precisely control the cut being made. U.S. Pat. No., 5,813,805 issued to Robert K. Kopras, describes a detachable handle for spiral cutting tools and other similar hand-held power tools. The detachable handle provides for extensive continuous use of the power tool while maintaining operator comfort and cutting tool control. The handle may be attached securely to the spiral cutting tool when the tool is to be used for extended periods of time, or generally to enhance the operator""s comfort and control in using the spiral cutting tool. The handle may be removed from the tool, for example, when the spiral cutting tool is to be used in tight quarters wherein the handle might become an obstacle to precise control of the spiral cutting tool. The handle is removably secured to the spiral cutting tool by threaded knobs that are inserted through mounting holes in the ends of the handle and tightly threaded into threaded holes formed in handle lugs extending from the motor housing. The threaded knobs are preferably designed so that the detachable handle may be secured tightly to the handle lugs by hand, without the need for a wrench or other tool. Although the threaded knobs may be tightened and removed by hand, they can take some time to thread and unthread from the handle, thereby increasing the time required for attaching the handle to and removing the handle from the motor housing. The detachable handle also features compartments formed therein for holding various spiral cutting tool accessories, such as extra spiral cutting tool bits and a wrench for securing the bits to the spiral cutting tool.
Many hand-held power tools include a power on/off switch mounted on the tool motor housing, rather than on a tool handle. In such tools, the tool motor cannot be controlled by the hand, usually the dominant hand, which is grasping the tool by the handle. Some hand-held power tools, therefore, have power on/off trigger switches mounted in or near the tool handle. However, such handles are not removable. Furthermore, such trigger switches are typically mounted in the handle of the power tool such that the trigger switch is operated by the forefinger, or forefinger and index finger, of the operator""s hand. These are typically the strongest fingers of the hand, which must be used, therefore, in such tools, to both hold and control the tool while simultaneously operating the trigger switch. This can increase fatigue and reduce the operator""s effective control of the tool.
The second significant factor in making a precise cut using a spiral cutting tool, or any other hand-held power tool, is operator visibility at the point of the cut. Such visibility can be reduced by a build-up of cutting debris, e.g., sawdust, removed from the workpiece by the tool at the point of a the cut, and poor lighting at the point of the cut. Some power tools employ vacuum systems connected to the tool to remove cutting debris from the point of the cut. However, the use of such a vacuum system often makes use of the tool more cumbersome. Proper lighting at the point of a cut can be a problem, both in generally poorly lighted construction environments and, more generally, in any environment where the operator of the tool and the tool itself cast a shadow over the workpiece at the point of the cut.
What is desired, therefore, is an improved spiral cutting tool, or other hand-held power tool, which includes features for improving operator control of the tool and operation visibility at the point of a cut being made using the tool.
The present invention provides an improved hand-held power tool, such as a spiral cutting tool, including features for improving an operator""s ability to operate the tool to provide a precise cut. The present invention provides a hand-held power tool with features for improving both operator control of the tool and operator visibility at the point of a cut being made using the tool.
The present invention provides an easily detachable handle for a spiral cutting tool and other similar hand-held power tools. The use of the detachable handle provides for extensive continuous use of the tool while maintaining operator comfort and tool control. The detachable handle of the present invention includes a gripping surface for an operator""s hand which is oriented substantially parallel with the axis of the tool housing. Precise control of the tool is maintained by grasping the tool with two hands, one on the handle, the other on the tool motor housing. The detachable handle facilitates positioning the tool with its axis perpendicular to the workpiece, and moving the tool along the plane of the workpiece in a direction perpendicular to the axis of the tool.
A detachable handle in accordance with the present invention is easily and quickly attachable to the motor housing of a spiral cutting tool, or other hand-held power tool, and is easily and quickly detachable therefrom. The detachable handle may be attached securely to the tool when the tool is to be used for extended periods of time, or generally to enhance the operator""s comfort and control in using the tool, and may be removed easily and quickly from the tool, for example, when the tool is to be used in tight quarters, where the detachable handle might become an obstacle to precise control of the tool.
A detachable handle in accordance with the present invention preferably has two handle ends, each of which is securely but detachably attachable to a hand-held power tool housing. This provides a very securely attachable and stable handle for the tool. The structures by which the handle is detachably attached to the tool housing preferably provide for easy and quick removal of the handle from the housing when desired. In accordance with the present invention, a detachable handle may include a fixed handle mounting structure, such as fixed tab projections, extending from one end of the handle, and a moveable handle mounting mechanism, such as a rotatable rod, extending from the other end of the handle. Fixed housing mounting structures, such as housing apertures, are formed in the tool housing and positioned therein for receiving the extending tabs and rotatable rod which extend from the ends of the handle. The extending tabs preferably are hook-shaped, such that the tabs may be hooked into the corresponding apertures formed in the tool housing. The rotatable rod preferably includes a distal radially extending portion formed at the distal end thereof, which is sized to fit through a slot formed in the corresponding aperture formed in the tool housing. The rotatable rod may be mounted in the corresponding aperture formed in the housing by rotating the rod so as to align the distal radially extending portion with the slot formed in the corresponding aperture formed in the housing. The rotatable rod is then rotated such that the distal radially extending portion is aligned perpendicularly to the slot, thereby preventing removal of the rod, and, therefore, the handle, from the aperture formed in the housing. A second radially extending portion may be formed on the rotatable rod to engage a threaded wall formed in the corresponding aperture in the tool motor housing. The second radially extending portion and threaded wall interact to pull the end of the handle tightly against the tool housing as the rod is rotated, to thereby secure the handle to the tool housing. The rotatable rod may preferably be rotated by a lever mechanism attached to the rod and extending from the detachable handle. The rotatable rod and lever are preferably mounted on the top or thumb end of the detachable handle. A thumb tab is preferably formed extending from the lever to facilitate movement of the lever by an operator""s thumb. The detachable handle may, therefore, be easily and quickly attached to the tool housing by an operator by inserting the extending tabs and rotatable rod into the apertures formed in the housing and operating the lever mounted on the detachable handle to rotate the rotatable rod to secure the handle to the housing. By operating the lever mounted on the detachable handle in the opposite direction, the detachable handle is easily and quickly removed from the housing.
A detachable handle in accordance with the present invention preferably includes one or more compartments formed therein, e.g., for holding and storing spiral cutting tool or other handle-held power tool accessories. The compartment may be accessible through an aperture formed in the detachable handle, which may be covered by a hinged door.
In accordance with the present invention, a detachable handle for a spiral cutting tool, or other hand-held power tool, preferably includes an on/off trigger switch, for activating the tool, mounted therein. The trigger switch is preferably mounted on an inside of the detachable handle, i.e., on the side of the handle facing the tool housing when the handle is attached to the tool. The trigger switch is preferably mounted at a lower end of the inside of the handle, such that the trigger switch is operable by the little finger (pinky) and ring finger of the operator""s hand. This allows the stronger middle finger, index finger, and thumb of the operator""s hand to be used solely for holding and controlling the tool to which the handle is attached.
The trigger switch mounted in the detachable handle is coupled to a motor in the tool motor housing such that the motor is activated when the trigger switch is actuated and the detachable handle is mounted on the power tool housing. The trigger switch is preferably coupled to the tool motor via a motor controller mounted in the housing without a mechanical connection between the trigger switch and the motor controller. Such a mechanical connection between the trigger switch, mounted in the detachable handle, and the motor controller, mounted in the motor housing, might interfere with the easy and quick attachment of the detachable handle to, and removal of the detachable handle from, the tool housing. The trigger switch mounted in the detachable handle may be coupled to a magnet, mounted on a moveable arm mounted in the detachable handle, which is moved toward the tool housing when the trigger switch is actuated by an operator and the detachable handle is mounted on the housing. A Hall effect sensor, or similar magnetic field sensor, is mounted within the tool housing to detect the movement or position of the magnet. The magnetic field sensor is thus employed to detect the movement of the magnet in response to the activation of the trigger switch. The sensor is coupled to the motor controller which activates the tool motor in response to the detection of the movement of the magnet. Thus, activation of the tool motor by a trigger switch mounted in a detachable handle is achieved without providing a mechanical connection between the trigger switch, mounted in the detachable handle, and the motor controller for controlling the tool motor, mounted in the tool housing, thereby providing a rugged trigger switch coupling mechanism which does not interfere with the easy and quick attachment and detachment of the detachable handle to and from the tool housing.
A spiral cutting tool, or other hand-held power tool, in accordance with the present invention preferably includes a multiple-position power on/off switch mounted on the tool housing. The multiple-position power switch is used in combination with the trigger switch mounted in the detachable handle for controlling the power on/off state of the tool motor. The multiple-position power on/off switch mounted on the tool housing preferably includes at least three operating positions. In a first operating position of the multiple-position power on/off switch, the tool motor is turned off and the trigger switch is disabled. Thus, when the multiple-position power on/off switch is in this first position, the tool motor will not be activated even if the trigger switch mounted on the detachable handle attached to the tool housing is actuated. In a second position of the multiple-position power switch, the trigger switch mounted in the detachable handle mounted to the tool motor housing is enabled. Thus, when the multiple-position power switch is in this second position, the tool motor is activated only when the trigger switch mounted in the detachable handle is actuated. In a third position of the multiple-position power switch, the tool motor is activated. As long as the multiple-position power switch is in this third position, the tool motor will be in operation, whether or not the trigger switch in the detachable handle is actuated (or the detachable handle is even attached to the tool housing). The multiple-position power on/off switch in accordance with the present invention thus allows an operator of a spiral cutting tool, or other hand-held power tool, fully to control the power on/off state of the tool motor, including controlling when the power on/off state of the tool may be controlled by the trigger switch mounted in the detachable handle.
A spiral cutting tool, or other hand-held power tool, in accordance with the present invention preferably includes a variable speed motor. The operating speed of the motor may be controlled by a speed control button and user interface which allows an operator of the tool to select the operating speed of the motor, and which presents to the operator a visual indication of the speed selected. A hand-held power tool motor may begin operation at an initial operating speed when the tool motor is first turned on, by use of either a multiple-position power switch mounted on the tool housing or a trigger switch mounted on a detachable handle attached to the tool housing. A speed control button is provided on the tool housing and coupled to a motor controller. Each time the speed control button is actuated, the motor controller changes the speed of the motor in response thereto. For example, each time the speed control button is actuated, the motor speed may increase or decrease one step from the then-current operating speed, until either the highest or lowest available operating speed is reached, at which point, upon the next actuation of the speed control button, the motor is controlled to decrease or increase motor speed by one step. For example, if four motor operating speeds are made available, the motor speed may be increased or decreased by three steps from the initial motor operating speed, by one step each time the motor speed control button is actuated. Upon the fourth actuation of the motor speed control button, if the motor speed is at its lowest setting, the motor will be controlled to increase the motor speed to the next higher speed. If the motor speed is at its highest setting, the motor will be controlled to decrease the motor speed to the next lower speed. (Alternatively, the motor may be controlled to return to its initial operating speed upon the next actuation of the speed control button after either the highest or lowest operating speed is reached.) the motor speed will return to the initial operating speed. Thus, a single button is employed to cycle the tool motor through the available operating speeds. Motor speed indicator LEDs may be mounted on the spiral cutting tool housing near the motor speed control button, and illuminated by the motor controller to indicate to the operator of the tool the current motor speed selected. The speed control button and LEDs are preferably covered by a single piece of flexible plastic, which protects the speed control interface from cutting debris, while allowing the speed control button to be operated therethrough and the speed indication LEDs to be visible therethrough.
A spiral cutting tool, or other hand-held power tool, in accordance with the present invention preferably also provides for improved visibility of a workpiece at the point of a cut being made by the tool. Improved visibility under poor lighting conditions is provided by one or more high-output LEDs mounted in the tool housing near a position where the tool""s motor shaft emerges from the housing, so as to direct a beam or beams of light toward a workpiece at the point of a cut being made by the tool. The LEDs may be mounted in aperture pockets or receptacles formed in the tool motor housing near the point where the tool motor shaft emerges from the tool. Multiple LEDs may be mounted in the tool housing at angles so as to provide beams of light which cross each other at the area of a cut. For example, at least two such high-output LEDs may be provided, which may be mounted on opposite sides of a tool motor shaft, in the tool housing, and at angles such that the beams provided by the high-output LEDs cross each other at a point which intersects with the axis of the tool motor shaft at a position in front of the tool motor shaft at which, e.g., a spiral cutting tool bit is to be mounted and at a point where the spiral cutting tool bit is cut into a workpiece. The LEDs may be controlled to turn on whenever the power switch is activated.
To further improve visibility of a workpiece being cut by a spiral cutting tool, or other hand-held power tool, the present invention provides for the clearing of cutting debris, e.g., sawdust, from a workpiece at the point of a cut being made by the tool. In accordance with the present invention, a spiral cutting tool, or other hand-held power tool, preferably includes a fan located within the motor housing and preferably attached to the motor shaft. When the motor is turned on, the fan is rotated at a high speed to draw air through the motor housing and across the tool motor to thereby cool the motor. One or more air exhaust vents may be formed in the motor housing at the end of the motor housing adjacent to the point where the motor shaft emerges from the motor housing, i.e., at the end of the shaft where a spiral cutting tool bit or other attachment is attached to the motor shaft. Air drawn through the motor housing by the fan is directed through the air vents onto the workpiece surface at the point of the cut, thereby blowing cutting debris away from the point of the cut, to enhance visibility thereof.
In some cases, e.g., for cutting gypsum board drywall, it may be preferred that cutting debris not be blown away from the point of a cut. In accordance with the present invention, a moveable air vent cover is provided. The moveable air vent cover is preferably mounted in the tool motor housing, and may be operated to close the vents in the motor housing which open toward the workpiece. The moveable air vent cover may also be formed to open other vents formed in the motor housing directed radially outward from the sides of the motor housing when the air vents directed toward the workpiece are closed. Air drawn through the motor housing to cool the motor may thereby be redirected in a direction radial to the tool, using the moveable air vent cover, so as to not disturb cutting debris from a workpiece being cut. The air vent cover may be implemented as a flat ring having vertically extending portions formed along an outer edge thereof. The flat ring includes apertures formed therein which may be aligned with the air vents formed in the end of the tool housing to allow exhaust air to be directed toward a workpiece being cut. The vertically extending portions are formed on the ring such that, when the ring is positioned such that the apertures formed therein are aligned with the air vents to allow air flow to be directed toward the workpiece, the vertically extending portions at least partially block the flow of air through other air vents formed in a sidewall of the tool housing. When the air vent cover is moved such that the apertures formed therein are moved out of alignment with the air vents directed toward the workpiece, to block the flow of air toward the workpiece, the vertically extending portions are moved away from the air vents formed in the side of the tool housing, to allow an increased flow of air therethrough. The air vent cover is preferably mounted in the tool housing for rotational movement therein, and may include a tab, lever, handle, or other structure attached thereto which extends from the housing, e.g., through a slot in the sidewall of the motor housing. Using this tab, the air vent cover may be rotated in the motor housing by an operator between positions allowing air flow through the air vents to be directed toward a workpiece, and blocking air flow toward the workpiece. Thus, an operator may direct a flow of air toward a workpiece to blow cutting debris therefrom, to enhance visibility of the workpiece surface at the point of a cut, or block such air flow, when desired.
The present invention thus provides a spiral cutting tool, or other hand-held power tool, having features which enhance the utility of the tool by providing for enhanced control and operation of the tool during use, and visibility of a workpiece being cut by the tool.
Further objects, features, and advantages of the invention will be apparent from the following detailed description of the invention, taken in conjunction with the accompanying drawings.